出乎意料的火星温度（图）   

 

Mars Colder Than Expected

Peering beneath the ice at the north pole of Mars has now revealed the red planet may be surprisingly colder than was thought. Any liquid water that might exist on Mars therefore might be hidden deeper than once suspected, closer to that world's warm heart, researchers suggested.	日前，对火星北极冰层以下的探测显示：这颗红色星球的温度可能远远低于过去的估计。因此研究人员提出，火星上可能存在的液态水或许也是深藏不露，出乎预料，其位置离火星温暖的核心部位更近。
An international team of scientists used the Mars Reconnaissance Orbiter to probe the north pole of the red planet with radar. The ice cap there goes about 1.2 miles deep (2 km) and is roughly the size of Pakistan at 310,000 square miles large (800,000 square km).	一个跨国科学研究小组利用装有雷达的“火星探测轨道飞行器”探测了这颗红色星球的北极，那里的冰帽大约有1.2英里（2公里）厚，范围大约跟巴基斯坦的大小相当，为31万平方英里（80万平方公里）。
These scans revealed the polar cap has up to four layers of ice rich in sand and dust, each separated by clearer sheets of nearly pure ice. Each dirty and clean layer is some 1,000 feet thick (300 meters).	这些扫描结果显示：北极冰帽拥有多达四层的富冰泥沙层，每层都有较为透明的几乎为纯冰的间层隔开，每一混浊层和每一透明层都大约厚1,000英尺（300米）。
These dirty and clean layers were created by ages of intense dust storms followed by icy eras. This five-million-year-long cycle was likely driven by wobbles in Mars' tilt and fluctuations in the shape of its orbit around the sun. The more sunlight the red planet saw because of these changes, the more the polar icecaps retreated and the more dust storms Mars saw.	这些混浊层和透明层是由于在多年的强烈尘暴过后，随即又经历冰期造成的，这个长达500万年的周期可能是由于火星倾斜度的变化以及绕日轨道的形状变化造成的。由于这些变化，火星接触的阳光越多，极地冰帽融化得就越多，经历的尘暴也就越多。
"All this layering is key evidence for theoretical models that predict that changes in Mars' climate are coupled with orbital changes," said researcher Roger Phillips, a geophysicist at Southwest Research Institute in Boulder.	“一些理论模型预测，火星气候变化跟其轨道的变化相关。所有的层状结构为这些理论模型提供了关键证据，”博尔德西南研究院的地球物理学家罗杰·菲利普斯说。
Unexpectedly, the radar scans also revealed the massive weight of the ice cap does not deform any underlying sediment. This implies the crust beneath the cap is strong — more than 180 miles thick (300 km).	出乎意料的是，雷达扫描还显示：冰帽的巨大重量并没有使下面的沉积层变形。这意味着冰帽下面的火星地壳是坚硬的，厚度超过180英里（300公里）。
To have such a thick crust, "Mars might be colder than we thought," Phillips told SPACE.com. As a result, any liquid water that might be underground has to be buried even deeper than once speculated. "If one thought that liquid water was 5 kilometers deep (3 miles), it's now at least 30 percent deeper than that," he said.	“如果拥有这么厚的地壳，火星温度或许会比我们原以为的要低，”菲利普斯告诉太空网的记者说。结果，比起以前的推测，可能存在于地下的液态水一定埋葬得更深。他说：“如果以前认为液态水处于5公里（3英里）的深处，现在至少在那个深度上还要增加30％。”
Philips and his colleagues detailed their findings online May 15 in the journal Science.	菲利普斯及同事将他们的发现详尽地描述在5月15日《科学》杂志的在线版上。
As to why Mars might be so cold, "perhaps it was robbed of its fair share of heat-producing elements, such as uranium and thorium, when it was first born," Phillips said. Or perhaps the way heat flows on Mars is quite variable, with the crust being colder and thicker at the poles and hotter elsewhere — "like Mars' volcanic provinces of Tharsis and Elysium."	至于火星为何这么冷，菲利普斯说：“也许火星一诞生就失去了那些应有的产生热量的元素，如：铀和钍。”或者，也许是因为火星的热量流动模式在很大程度上变化不定，造成极地的地壳较为寒冷和厚重，而其他地方则较为炎热——如：火星上的塔西斯和埃利泽姆等火山区。
The upcoming Phoenix Lander mission, which will explore the water ice just underneath the surface soil of the Martian arctic plains, might help shed light on the layering at Mars' north pole. To solve the mystery of the heat of Mars, heat flow probes are likely needed all over that planet, as is suggested by the Mars Network Mission under proposal, Phillips said.	即将实施的“凤凰号火星着陆”计划，将要探测火星北极平原表层土壤下面的水冰，该计划也许有助于揭示火星北极的层状结构。菲利普斯指出，要想揭开火星的热量之谜，可能需要将热量流动探测器布满全球，正象提议的“火星网络计划”所建议的那样。